Monitoring fiber for a machine and method of installation

ABSTRACT

An electric machine assembly and a method of installing an electric machine assembly, the electric machine including a downhole electric machine; and a fiber operatively arranged at least partially through a housing of the electric machine for sensing at least one parameter of the electric machine assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 61/527,654 filed Aug. 26, 2011, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Hot spots in motors, generators, and other electric machines, particularly in the windings thereof, indicate that the machines are potentially failing or operating improperly. Current systems include resistive thermal devices (RTDs) and other thermocouples, but these are installed only at discrete locations near the machine and cannot measure a temperature distribution across the entire machine or within the machine. Furthermore, the accuracy of RTDs and other thermocouples suffers as they are heavily influenced by electromagnetic noise generated by the machines. Other parameters indicating potential failure or improper operation include strain, acoustics, etc., which are similarly difficult to monitor. A machine failure is particularly disadvantageous when the access to the machine is limited, for example, if the machine is a motor for an electric submersible pump installed on a downhole tubular string. Accordingly, the downhole drilling and completions industry, well receive advances in machine monitoring systems and assemblies.

BRIEF DESCRIPTION

An electric machine including a downhole electric machine; and a fiber operatively arranged at least partially through a housing of the electric machine for sensing at least one parameter of the electric machine assembly.

A method of installing a fiber in a downhole electric machine for monitoring the electric machine including arranging at least one fiber at least partially through a housing of a electric machine, running the electric machine downhole, and sensing at least one parameter of the electric machine with the fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a cross-sectional view of a portion of a housing of a machine including a fiber feed through assembly;

FIG. 2 is a cross-sectional view of the feed through assembly of FIG. 1;

FIG. 3 is a cross-sectional view of an installation assembly for the feed through assembly of FIG. 2;

FIG. 4 is a cross-sectional view of a transition for installing a fiber through stacked or tandem machines;

FIG. 5 is an enlarged view of the transition of FIG. 4;

FIG. 6 schematically illustrates a turn around tube for facilitating installation of fibers; and

FIG. 7 is a cross-sectional view of a machine having a capped port for isolating an interior of the machine.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring now to FIG. 1, a machine 10 is partially shown. The machine 10 is an electric machine such as a motor, a generator, etc. Other motors such as mud motors can also be monitored by systems according to the current invention as disclosed herein. In one embodiment, the machine 10 is a motor for an electric submersible pump (ESP) arranged on a tubular string in a borehole, although other arrangements are possible. The machine 10 includes a feed through assembly 12 for a housing 14. The housing 14 is, for example, a motor head in embodiments in which the machine 10 is a motor, although the housing 14 could take other forms in other embodiments. The feed through assembly 12 is arranged to enable access into and out of the housing 14. In some embodiments, the feed through assembly 12 is also arranged to seal a lubricating or operating fluid located in an internal chamber 16 of the machine 10, generally defined by the housing 14, from an annulus 18.

One embodiment of the assembly 12 is illustrated in more detail in FIG. 2. Specifically, the assembly 12 is illustrated in an installed configuration with respect to a port 20 for the housing 14. A primary feed through block or plug 22 includes a plurality of passages 24 therethrough. Each passage 24 is arranged to receive a conduit or carrier, such as a capillary tube 26. Each capillary tube 26 is arranged to receive at least one fiber, e.g., the capillary tube 26 in FIG. 2 includes a fiber 28 therein. For the sake of discussion and clarity, only two passages 24 are shown and only one of the passages 24 includes the capillary tube 26 installed therein and housing the fiber 28. Of course, it is to be appreciated that any number of passages 24 could be included in the block 22 with any number of the capillary tubes 26 having any number of the fibers 28. The fiber 28 is arranged, for example, for sensing parameters of the machine 10, such as temperature, acoustics, vibration, strain, etc. For example, if the machine is an electric machine, temperature could be sensed to monitor whether windings or other components of the machine are overheating, indicating potential failure of the machine. If the machine is a mud motor or other motor, vibration, temperature, stress, etc. of the stator or other components can be monitored to determine whether the motor is operating within desired parameters. The fibers are arrangable at any suitable location at the machine that enables the fibers to sense, measure, monitor, detect, etc., the desired parameter or component of the machine. In one embodiment, the fiber 28 is an optical fiber using fiber Bragg gratings, distributed temperature sensing (DTS), etc. to sense parameters of the machine 10. Fiber Bragg gratings have advantageously been shown to provide about a 2cm resolution in temperature sensing applications. In strain and acoustic monitoring embodiments, for example, the fibers could be loosely threaded through the capillary tubes 26, or an adhesive, epoxy, etc., could be pumped into the capillary tubes to secure the fibers to the tubes.

An engagement 30 may be included between the block 22 and the port 20, e.g., as complementarily formed profiles, for setting a position of the block 22 in the port 20. At least one seal element 32, such as an o-ring or the like, is disposed about the block 22 for sealing the port 20. A pin 34 or other key or feature is disposed between the block 22 and the housing 14 for rotationally locking the assembly 12 in the port 20. An intermediary block 36, described in more detail below, is similarly rotationally locked to the block 22 via a pin 38. A ferrule 40 or some other seal element is included at a mouth 42 of each passage 24 between the blocks 22 and 36 for sealing the passage 24 with respect to the internal chamber 16 of the machine 10.

In some embodiments, the intermediary block 36 is used during installation of the assembly 12. For example, an installation assembly 44 is shown in FIG. 3. The block 22 is installed first, for example, as described above, e.g., by landing the block 22 at the engagement 30, rotationally locking the block 22 via the pin 34, and inserting the capillary tubes 26 into the passages 24. After installation of the block 22, the intermediary feed-through block 36, a setting block 46 or other setting component, and a setting tube 48 are inserted into the port 20. A fiber installation tube 50 corresponding to each of the capillary tubes 26 is run through the setting tube 48, a passage 52 in the setting block 46, and terminates in a passage 54 in the intermediary block 36. The passages 54 each include a mouth 56 for receiving a ferrule 58 or other seal element. The setting tube 48 or some other component then exerts a force on the setting block 46 and the intermediary block in order to set the ferrules 40 and 58, respectively, and thus seal the passages 24 and 54. For example, the setting tube 48 is engagable with threads 60 in the housing 14, such that rotating the setting tube 48 exerts an increasingly large force on the ferrules 40 and 58 via the blocks 36 and 46, respectively.

Once the ferrules 40 and 58 have been set, the capillary tubes 26 are aligned with the tubes 50 in the passages 54 and the fibers, e.g., the fiber 28 (not shown in FIG. 3), can be pumped, injected, installed, or otherwise fed into the installation tubes 50 and into the capillary tubes 26. Before installing the fiber, however, it may be desirable to first test the seals, for example, as formed by the ferrules 40 and 58, the seal elements 32, etc. In one embodiment, a fluid inert to the operating or lubricating fluid in the internal chamber 16 of the machine 10, e.g., nitrogen, the operating/lubricating fluid itself, etc., is pumped down to test the ferrules and any other seals. Optionally, the test fluids could be pumped down the tubes 50, into a cavity 62 between the primary block 22 and the intermediary block 36 (e.g., by extending a bore 64 in the block 36 into the cavity 62), etc. After testing the seals, the fibers 28 can be fed into the tubes 26 as noted above, the installation assembly 44 removed, and the fibers 28 cut to appropriate lengths.

Referring now back to FIG. 2, after installation, a portion of each capillary tube 26 extends into respective ones of the passages 54 in the intermediary block 36. The passages 54 are in communication with a cavity 66 in a combining block 68 of the assembly 12. The cavity 66 directs all of the fibers 28 into a single conduit 70, which extends from the block 68, e.g., to a splice housing or the like, where the fibers 28 can be spliced to a main downhole cable. The block 68 may include a seal element 72, e.g. an o-ring, for sealing the assembly 12 from the annulus 18.

Machines such as motors are occasionally stacked or included in tandem in order to increase the overall power output. For example, see United States Patent No. 2007/0224057, which patent is hereby incorporated by reference in its entirety. A transition is disclosed in FIG. 4 for forming a fiber passageway through two or more stacked motors or other machines. FIG. 4 shows an upper machine housing 14 a for a first machine and a lower machine housing 14 b for a second machine. A first tandem feed through assembly 12 a is included in the housing 14 a and a second tandem feed through assembly 12 b is included in the housing 14 b. Some elements of the assemblies 12 a and 12 b resemble those of the assembly 12 and have been labeled accordingly with similar reference numerals.

A transition tube 76 is included bridging between the two machine housings 14 a and 14 b. The transition tube 76 includes, for example, seal elements 76 for sealing the ends of the capillary tubes 26, which are disposed in passages 78 in the transition tube. By use of the transition tubes 74, any number of machines can be stacked together, with the stacked machines isolated from each other and from borehole pressures and fluids. For example, in one embodiment, the machines take the form of motors that are installed in a borehole. In this embodiment, the lower motor having the housing 14 b is first installed and filled with oil or other operating fluid. Then, the transition tube 74 can be installed when the top motor having the housing 14 a is stacked onto or stabbed into the lower motor. In some embodiments, the passages 78 of the transition tube 74 include enlarged mouths 80 for facilitating the stacking or stabbing of the transition tube 74 onto the capillary tubes 26 already installed in the bottom motor. After stabbing or stacking the motors together with the transition tube 74 therebetween, the top motor can be filled with oil or other operating fluid, and then the assembly 12 installed as described with respect to FIG. 3. Generally, once both machines are installed, fiber can be fed or injected into the capillary tubes down through both machines for monitoring parameters of both machines.

Alternatively, of course, it is to be appreciated that the transition tube 74 and assemblies 12 a and 12 b could be replaced with other transitions or transition elements, such as optical connectors or other optical connections. For example, in one embodiment, the assemblies 12 a and 12 b are each replaced by male optical connectors, while the transition tube is replaced by a female-female optical connector that engages with the male connectors, or vice versa, or other combinations disclosed herein mutatis mutandis. In another embodiment, a first fiber is fed into the bottom motor and a second fiber is fed into the top motor and the two fibers are connected optically in some other way, such as a fusion splice, a mechanical splice, etc. In this way, a transition could comprise any optical connection or connector between two or more existing fibers and is not limited to a passage for a single fiber to be fed therethrough.

In one embodiment, the machine 10 is a three-phase induction motor. These and other motors are well known and used in a variety of applications. Accordingly, the motor has three pairs of windings corresponding to each of the phases. Each of the six windings forms a rather large oval within a portion of the motor housing. The capillary tubes 26 could be arranged through, in, or next to the windings or a stator of the motors in which they are installed. Furthermore, there could be one tube 26 for each winding of the motor 10 for monitoring parameters, e.g., temperature, of each winding. It is to be appreciated that other types of motors or other machines could be used, and that any other number of capillary tubes could be used, regardless of the number of windings or other components to be monitored in the machines. Of course, the fibers could be located or installed in any desired location within a motor or other electric machine. In such embodiments in which the machine 10 is an induction motor, the capillary tubes 26 can be made from durable, non-magnetic materials, so that they do not interfere with the operation of the motor and can withstand the operating fluids contained in the motor. In one embodiment, the capillary tubes are made from polyether ether ketone.

In one embodiment, the capillary tubes 26 are arranged in pairs. For example, in FIG. 6 a pair of tubes 26 a and 26 b are affixed together, for example, with a turn around tube 26 c at an end opposite the assembly 12. In this way, a fiber can be continuously injected into a first tube, e.g., the tube 26 a until the fiber is ejected from the top of the second tube, e.g., the tube 26 b. Advantageously, this can be used to reduce the number of fibers that must be installed in the system, as the same fiber can be used to monitor two different windings or locations. Alternatively, fibers can be fed down both of the tubes in the pair for providing a level of redundancy. In some embodiments in which a multiple pairs of windings are included in the machine 10, the tube pairs can be arranged so that both tubes in the pair are arranged with windings of the same phase or with windings of different phases. In some embodiments including multiple stacked machines, such as described with respect to FIGS. 4 and 5, the turn around tube 26 c is installed downhole of the downhole-most machine.

Cleanliness of the machine 10, particularly that of the inner chamber 16 and the operating fluid, is paramount to the longevity and proper functioning of the machine. Accordingly, FIG. 7 illustrates a cap block 82, which can be pre-installed in the port 20 of the machine 10 in order to seal the inner chamber 16 of the machine. For example, in the illustrated embodiment, the cap block 82 is securable to the primary feed-through block 22 via a bolt 84 and includes a seal element 86 disposed radially therewith. Also in the illustrated embodiment, the ends of the capillary tubes 26 are held in bores 88 in the block 82 in order to also seal the capillary tubes 26. In this way, the machine 10 can be shipped, at least partially installed, etc., without contaminating the inner chamber 16 of the machine 10.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

What is claimed is:
 1. An electric machine assembly, comprising: a downhole electric machine; and a fiber operatively arranged at least partially through a housing of the electric machine for sensing at least one parameter of the electric machine assembly.
 2. The assembly of claim 1, wherein the fiber is disposed in a capillary tube extending into the electric machine housing.
 3. The assembly of claim 2, wherein the capillary tube isolates the fiber from a fluid in the electric machine.
 4. The assembly of claim 3, wherein a seal element is disposed about the capillary tube for sealing in the fluid.
 5. The assembly of claim 3, wherein the capillary tube extends from outside the housing to inside the housing through a passage in a feed through block sealed in a port of the housing.
 6. The assembly of claim 5, wherein the feed through block is non-rotationally locked to the housing.
 7. The assembly of claim 5, wherein the capillary tube is one of a plurality of capillary tubes, the fiber is one of a plurality of fibers, and each capillary tube includes at least one of the fibers therethrough.
 8. The assembly of claim 7, further comprising a combining block located in the port of the housing, the combining block in communication with each of the capillary tubes for directing each of the fibers into a single fiber conduit extending out from the electric machine.
 9. The assembly of claim 5, wherein the feed through block is operatively arranged to receive a cap block thereon, the cap block enabling a pre-assembly configuration by sealing the port and the capillary tubes.
 10. The assembly of claim 1, wherein the fiber is one of a plurality of fibers and the plurality of fibers are arranged to detected the at least one parameter at a plurality of locations in the electric machine.
 11. The assembly of claim 1, wherein the electric machine assembly is for a three phase motor having three pairs of windings.
 12. The assembly of claim 11, wherein the fiber is one of a plurality of fibers and the plurality of fibers are arranged within each of the windings.
 13. The assembly of claim 1, wherein the parameter comprises temperature, strain, acoustics, or combinations including at least one of the foregoing.
 14. The assembly of claim 1, further comprising a second electric machine and a transition bridging between the electric machine and the second electric machine, the fiber extending from the electric machine to the second electric machine.
 15. The assembly of claim 14, wherein the fiber comprises a first fiber connected to a second fiber.
 16. The assembly of claim 15, wherein the first and second fibers are connected by corresponding optical connectors, a mechanical splice, a fusion splice, or combinations including at least one of the foregoing.
 17. The assembly of claim 1, wherein the fiber comprises optical fiber.
 18. The assembly of claim 1, wherein the capillary tube is one of a plurality of capillary tubes, the capillary tubes being arranged at least one pair, each pair having a turn around connecting both capillary tubes in that pair for enabling a single fiber to extend through both capillary tubes in each pair.
 19. A method of installing a fiber in a downhole electric machine for monitoring the electric machine comprising: arranging at least one fiber at least partially through a housing of a electric machine; running the electric machine downhole; and sensing at least one parameter of the electric machine with the fiber.
 20. The method of claim 19, wherein arranging the fiber further comprises: arranging a feed through block in a port of the housing of the electric machine; inserting a capillary tube through a passage in the feed through block, a seal element disposed about the capillary tube at a mouth of the passage; engaging a setting component in the port; setting the sealing element by exerting a pressure on the seal element with the setting component for sealing the port; and installing the fiber in the capillary tube.
 21. The method of claim 20, wherein arranging the at least one fiber further comprises: arranging a first capillary tube through a first port in the electric machine; arranging a second capillary tube through a second port in a second electric machine; engaging the first and second electric machines; feeding the at least one fiber through the first capillary tube and the second capillary tube; monitoring at least one parameter of the first and second electric machines with the fiber.
 22. The method of claim 21, wherein the at least one fiber includes a first fiber disposed in the first capillary tube and a second fiber disposed in the second capillary tube, where an optical connection is formed between the first and second fibers.
 23. A motor assembly, comprising: a downhole motor; and a fiber operatively arranged at least partially through a housing of the motor for sensing at least one parameter of the motor assembly. 